Plastering materials, typically cement mortar compositions are commonly applied with trowels. In the past, glue obtained from seaweed such as red algae is added to cement mortar compositions to ensure effective operation upon application. Then water-soluble cellulose ethers were developed as semi-synthetic resin and are widely used.
The cement mortar compositions are required to have several physical properties including good workability (easy to apply or finish with a trowel), high water retention (to prevent under-setting due to dry-out), and anti-sagging (to prevent tiles from slipping out of place). These requirements become severer as working sites become more efficient.
For example, Patent Document 1 proposes to use a methyl cellulose thickener and a modified starch. Since the grade of a starting material or origin for the modified starch is not specified, the method of Patent Document 1 sometimes fails to meet the desired properties. For example, the efficiency of trowel application is not fully improved, and the setting time is substantially prolonged.